US4915077A - Air-fuel ratio control apparatus - Google Patents

Air-fuel ratio control apparatus Download PDF

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Publication number
US4915077A
US4915077A US07/249,736 US24973688A US4915077A US 4915077 A US4915077 A US 4915077A US 24973688 A US24973688 A US 24973688A US 4915077 A US4915077 A US 4915077A
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United States
Prior art keywords
air
engine
pump current
fuel ratio
oxygen
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Expired - Lifetime
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US07/249,736
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English (en)
Inventor
Masanobu Uchinami
Toshihisa Takahashi
Hitoshi Inoue
Shinichi Nishida
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Assigned to MITSUBISHI DENKI KABUSHIKI KAISHA reassignment MITSUBISHI DENKI KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: INOUE, HITOSHI, NISHIDA, SHINICHI, TAKAHASHI, TOSHIHISA, UCHINAMI, MASANOBU
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1473—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the regulation method
    • F02D41/1475—Regulating the air fuel ratio at a value other than stoichiometry
    • F02D41/1476—Biasing of the sensor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/4065—Circuit arrangements specially adapted therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B1/00—Engines characterised by fuel-air mixture compression
    • F02B1/02—Engines characterised by fuel-air mixture compression with positive ignition
    • F02B1/04—Engines characterised by fuel-air mixture compression with positive ignition with fuel-air mixture admission into cylinder

Definitions

  • the present invention relates to an air-fuel ratio control apparatus with an oxygen pump type air-fuel ratio sensor formed by an ion conductive solid electrolyte to detect an air-fuel ratio by measuring an oxygen concentration in exhaust gas from an internal combustion engine.
  • an air-fuel control apparatus which comprises an air-fuel ratio sensor comprising a gap portion for introducing exhaust gas generated from an engine, a solid electrolyte oxygen pump for controlling a partial pressure of oxygen in the gap portion and a solid electrolyte oxygen sensor producing an electromotive force in response to a proportion of the partial pressure of oxygen in the gap portion and a partial pressure of oxygen in other than the gap portion, an electronic control device including a pump current stopping means which controls a pump current from the solid electrolyte oxygen pump so that the electromotive force generated by the solid electrolyte oxygen sensor is maintained at a constant value, and controls not to feed the pump current when the engine is stopped, and a control device which operates the optimum quantity of fuel supply to thereby effect an air-fuel control by a gas mixture producing mean in an operational condition that the engine is not subjected to a feed-back control on the basis of an output signal from the air-fuel ratio sensor, and controls not to feed a pump current by the
  • FIG. 1 is a diagram of an embodiment of the air-fuel ratio control apparatus according to the present invention.
  • FIG. 2 is a cross-sectional view taken along a line II--II in FIG. 1 which shows an air-fuel sensor used for the embodiment of the present invention
  • FIG. 3 is a characteristic diagram of the air-fuel ratio sensor shown in FIG. 2;
  • FIG. 4 is a flow chart showing a series of steps for operating the air-fuel ratio control apparatus of the present invention.
  • FIG. 1 there is shown schematically an embodiment of the air-fuel ratio control apparatus of the present invention, and a sectional view taken along a line II--II in FIG. 1.
  • a reference numeral 1 designates an exhaust pipe for an engine and a numeral 2 designates an air-fuel ratio sensor disposed in the exhaust pipe 1.
  • the air-fuel ratio sensor 2 comprises a solid electrolyte oxygen pump 6 (hereinbelow, referred to as an oxygen pump) which is constituted by a flat ion conductive solid electrolyte (stabilized zirconia) plate 3 having a thickness of about 0.5 mm and electrodes 4, 5 made of platinum attached to both side surfaces of the plate 3, a electrolyte oxygen sensor 10 (hereinbelow, referred to as an oxygen sensor) which is constituted by a flat ion conductive solid electrolyte plate 7 and electrodes 8, 9 made of platinum attached to both side surfaces of the plate 7 in the same manner as the oxygen pump 6 and a supporting block 11 to support the oxygen pump 6 and the oxygen sensor 10 so that they face with a minute gap d of about 0.1 mm.
  • a solid electrolyte oxygen pump 6 hereinbelow, referred to as an oxygen pump
  • an oxygen pump a flat ion conductive solid electrolyte (stabilized zirconia) plate 3 having a thickness of about 0.5 mm and
  • a numeral 12 designates an electronic control apparatus which is constituted in such a manner that an electromotive force e produced between the electrodes 8, 9 of the oxygen sensor 10 is applied to an reversing input terminal (negative) of an operational amplifier A through a resistor R 1 .
  • a transistor TR is actuated by the output of the operational amplifier A which is in proportion to the difference between a reference voltage V s (obtained by a power source V 1 ) applied to a non-reversing input terminal (positive) of the operational amplifier A, whereby a pump current I p flowing between the electrodes 4, 5 of the oxygen pump 6 is controlled.
  • the electronic control apparatus 12 functions to supply the pump current I p necessary to keep the electromotive force e at a predetermined value of V s .
  • the transistor TR is constituted by a pair transistors TR.
  • the collectors of the transistors TR are respectively grounded through respective power sources B, and the emitters are used commonly to be connected to the electrode 4 of the oxygen pump 6 through a resistor R o . Both ends of the resistor R o is connected to input ends of an ampere-volt transducer 13.
  • the resistor R o is to produce an output signal corresponding to the pump current I p supplied from the direct power sources B as a pump current supplying means.
  • the bases of the transistors TR are connected to the collector of a transistor TR 1.
  • the emitter of the transistor TR 1 is grounded and the base is connected to an output interface circuit 24.
  • the transistor TR 1 is to control the pump current being to be stopped or supplied.
  • the transistor TR 1 forms a pump current stopping means and is controlled by a control device 14 which is described below.
  • a capacitor C is connected between the output terminal of the operational amplifier A and the reversing input terminal of the amplifier A. The detail of the control device 14 will be described.
  • a numeral 20 designates an AD converter for converting an analogue output from the ampere-volt transducer 13 and information of intake air quantity into digital values
  • a numeral 21 designates a micro-processor for effecting arithmetic operations and logical treatments in accordance with programs stored in an ROM 22
  • a numeral 23 designates an RAM temporally storing values operated by the micro-processor 21
  • a numeral 24 an output interface circuit which receives a result of the arithmetic operations and the logical treatments of the micro-processor 21, and outputs a signal to actuate the pump current stopping means in the electronic control device 12 and a signal to control an amount of fuel supplied to a gas mixture producing means 15 or an amount of intake air
  • a numeral 25 designates an input interface circuit for receiving a signal indicative of an engine revolution number from a crank angle sensor (not shown).
  • a nemeral 16 designates an internal combustion engine and a numeral 17 designates a key switch.
  • FIG. 3 shows the relation between an air-fuel ratio and a current supplied from an oxygen pump in the case that an air-fuel ratio sensor 2 is attached to a gasoline engine.
  • the reason why the pump current I p varies in proportion to an air-fuel ratio in the region of air-fuel ratio A/F greater than a theoretical air-fuel ratio is described in Japanese Unexamined Patent Publication No. 130649/1981. Namely, an electromotive force e is produced in the oxygen sensor 10 when a partial pressure of oxygen contained in exhaust gas in the minute gap portion d is different from a partial pressure of oxygen in the exhaust gas flowing in the exhaust pipe 1.
  • a pump current I p varies in proportion to an concentration of oxygen in the exhaust gas when the pump current I p supplied to the oxygen pump 6 is controlled so that the electromotive force e approaches a predetermined value. Since the air-fuel ratio is substantially in proportion to the oxygen concentration, the pump current I p varies in proportion to the air-fuel ratio A/F.
  • the change of the pump current I p in the region of values smaller than the theoretical air-fuel ratio is likely caused by the fact that the air-fuel ratio sensor 2 is sensitive to the concentration of carbon monoxide (CO) in the exhaust gas.
  • CO carbon monoxide
  • the electronic control device 12 In the function of the electronic control device 12, there is no problem when the gasoline engine normally operates. However, when the engine is stopped, or becomes a conductive state by the actuation of the key switch 17 to start the engine and then, it is left for a while, the electronic control device 12 increases the supply of the pump current I p so that the electromotive force e of the oxygen sensor 10 is kept at a predetermined value V s . However, because of the engine stopped, there is too much amount of oxygen in comparison with the operation of the engine, whereby the value of the pump current I p becomes large. When such condition continues for a long time, the stabilized zirconia forming a part of the oxygen pump 6 or the electrodes to take out the pump current become deteriorated, whereby it is impossible to use it as a sensor.
  • the present invention is to prevent the elements of the air-fuel ratio sensor from deteriorating irrespective of the operational conditions of the engine and to block a pump current by detecting the stop of the engine.
  • a pump current I p is converted to have a voltage level by the ampere-volt transducer 13 and the output signal of the ampere-volt transducer 13 is supplied to the control device 14 and then, the control device 14 supplies a signal to the gas mixture producing means 15.
  • the control device 14 receives a signal indicative of a revolution number of engine to detect a state of engine stop, and an output signal is supplied to the electronic control device 12 to stop the pump current.
  • an analogue value indicating information of intake air quantity is converted into a digital value by the AD converter 20, and the micro-processor 21 operates to obtain the optimum quantity of fuel supply by using steps and constants which are previously stored in the ROM 22.
  • Data obtained by the operations are supplied to the gas mixture producing means 15 through the output interface circuit 24.
  • the data obtained by the operations correspond to the width of a driving pulse signal for an electromagnetic fuel injection valve 15 provided in the gas mixture producing means 15, whereby control of the air-fuel ratio is carried out by the gas mixture producing means 15.
  • the operations conducted without the feed-back control i.e. an opened loop control are corrected by the pump current I p .
  • the correction includes an appropriate ripple in a PI (proportioning and integrating) control.
  • Step 401 the number of revolution of the engine is detected at Step 401.
  • Step 402 determination is made as to whether or not the revolution number is higher than a predetermined value such as 30 rpm.
  • a detected value is lower than the predetermined value, determination is made so that the engine is stopped.
  • Step 403 is taken.
  • Step 404 is taken.
  • an output signal for stopping the pump current is supplied from the micro-processor 21 through the output interface circuit 24 to the transistor TR 1 in the electronic control device 12 to thereby change a potential at the basis of the transistors TR to the ground potential so that the pump current I p is stopped.
  • Step 404 an output signal for supplying the pump current I p in correspondence to a detected air-fuel ratio is supplied from the micro-processor 21 through the output interface circuit 24 to the transistor AR 1 in the same manner as the Step 403.
  • a pump current from an oxygen pump is stopped by actuating a pump current stopping means in an electronic control device on the basis of the output of a control device when the engine is found to be stopped by detecting the number of revolution of the engine. Accordingly, deterioration of an air-fuel ratio sensor element can be eliminated irrespective of the operational conditions of the engine.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biochemistry (AREA)
  • Immunology (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Electrochemistry (AREA)
  • Pathology (AREA)
  • Molecular Biology (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
US07/249,736 1987-10-22 1988-09-26 Air-fuel ratio control apparatus Expired - Lifetime US4915077A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP62-268457 1987-10-22
JP62268457A JPH0758053B2 (ja) 1987-10-22 1987-10-22 空燃比制御装置

Publications (1)

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US (1) US4915077A (de)
JP (1) JPH0758053B2 (de)
DE (1) DE3835958A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5518600A (en) * 1993-12-28 1996-05-21 Mitsubishi Denki Kabushiki Kaisha Oxygen concentration detection apparatus
WO2003088444A2 (de) * 2002-04-12 2003-10-23 Endress + Hauser Conducta Gmbh+Co. Kg Messeinrichtung für die flüssigkeits- und/oder gasanalyse

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2759168B1 (fr) * 1997-01-31 1999-04-02 Sagem Dispositif de mesure de la teneur d'un milieu gazeux en oxygene

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4665874A (en) * 1985-09-26 1987-05-19 Honda Giken Kogyo Kabushiki Kaisha Device for sensing an oxygen concentration in gaseous body with a pump current supply circuit and an air/fuel ratio control system using an oxygen concentration sensing device
US4698209A (en) * 1985-06-21 1987-10-06 Honda Giken Kogyo Kabushiki Kaisha Device for sensing an oxygen concentration in gaseous body with a source of pump current for an oxygen pump element
US4707241A (en) * 1985-03-07 1987-11-17 Nissan Motor Co., Ltd. Air/fuel ratio control system including means to well time start of feedback
US4753203A (en) * 1985-02-25 1988-06-28 Ngk Spark Plug Co., Ltd. Air/fuel ratio sensor apparatus for use with internal combustion engine
US4762604A (en) * 1986-03-19 1988-08-09 Honda Giken Kogyo Kabushiki Kaisha Oxygen concentration sensing apparatus
US4765298A (en) * 1986-09-30 1988-08-23 Mitsubishi Denki Kabushiki Kaisha Air-fuel ratio control system for internal combustion engines

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4272329A (en) * 1980-03-03 1981-06-09 Ford Motor Company Steady state mode oxygen sensor and method
JPS58133463A (ja) * 1982-02-03 1983-08-09 Toyota Motor Corp 内燃機関の空燃比制御装置
JPS60104734A (ja) * 1983-11-11 1985-06-10 Nissan Motor Co Ltd 空燃比制御装置
JPS60128349A (ja) * 1983-12-15 1985-07-09 Mitsubishi Electric Corp 空燃比検知装置
JPS6281559A (ja) * 1985-10-05 1987-04-15 Ngk Spark Plug Co Ltd 空燃比センサ

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4753203A (en) * 1985-02-25 1988-06-28 Ngk Spark Plug Co., Ltd. Air/fuel ratio sensor apparatus for use with internal combustion engine
US4707241A (en) * 1985-03-07 1987-11-17 Nissan Motor Co., Ltd. Air/fuel ratio control system including means to well time start of feedback
US4698209A (en) * 1985-06-21 1987-10-06 Honda Giken Kogyo Kabushiki Kaisha Device for sensing an oxygen concentration in gaseous body with a source of pump current for an oxygen pump element
US4665874A (en) * 1985-09-26 1987-05-19 Honda Giken Kogyo Kabushiki Kaisha Device for sensing an oxygen concentration in gaseous body with a pump current supply circuit and an air/fuel ratio control system using an oxygen concentration sensing device
US4762604A (en) * 1986-03-19 1988-08-09 Honda Giken Kogyo Kabushiki Kaisha Oxygen concentration sensing apparatus
US4765298A (en) * 1986-09-30 1988-08-23 Mitsubishi Denki Kabushiki Kaisha Air-fuel ratio control system for internal combustion engines

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5518600A (en) * 1993-12-28 1996-05-21 Mitsubishi Denki Kabushiki Kaisha Oxygen concentration detection apparatus
WO2003088444A2 (de) * 2002-04-12 2003-10-23 Endress + Hauser Conducta Gmbh+Co. Kg Messeinrichtung für die flüssigkeits- und/oder gasanalyse
WO2003088444A3 (de) * 2002-04-12 2004-03-25 Conducta Endress & Hauser Messeinrichtung für die flüssigkeits- und/oder gasanalyse

Also Published As

Publication number Publication date
DE3835958A1 (de) 1989-05-03
DE3835958C2 (de) 1990-12-13
JPH0758053B2 (ja) 1995-06-21
JPH01110855A (ja) 1989-04-27

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